Simplify the following expression: $r = \dfrac{-7p + 9}{5p + 7} \div \dfrac{1}{7}$
Answer: Dividing by a number is the same as multiplying by its inverse. $r = \dfrac{-7p + 9}{5p + 7} \times \dfrac{7}{1}$ When multiplying fractions, we multiply the numerators and the denominators. $r = \dfrac{(-7p + 9) \times 7} {(5p + 7) \times 1}$ $r = \dfrac{-49p + 63}{5p + 7}$